2 of America's biggest truckers are merging to form a $US5 billion industry giant

Knight Transportation and Swift Transportation have agreed to merge to create a North American trucking giant.

The merged firm, to be called Knight-Swift, will have a holding-company structure while maintaining the distinct brands, according to a statement Monday.

In an all-stock transaction, each Swift share will convert into 0.72 shares of the merged company. Each Knight share will be swapped for one Knight-Swift share.

The deal would help Knight and Swift take on their competitors amid plunging orders for some companies like Volvo Trucks North America. The rise of e-commerce is also changing their industry, as volumes and costs rise to meet new demand for home delivery.

The two companies earned about $US5.1 billion in total revenue and $US416 million in adjusted operating income last year. The companies expect to achieve about $US15 million in cost-saving synergies and pretax revenue in the second half of 2017, and up to $US150 million in 2019.

“By coming together under common ownership, the companies will be able to capitalise on economies of scale to achieve substantial synergies,” Richard Dozer, Swift’s chairman, said in a statement.

Knight’s CEO, Dave Jackson, will become chief executive of the merged company. Knight-Swift will have 23,000 tractors and employ 28,000 people.

Swift shares gained as much as 14% in premarket trading after the news.